The nuclear threat is as great today as it has ever been

THERE'S a joke doing the rounds. Kim Jong-un the North Korean dictator says: "I demand a telephone conversation with Obama. But first I demand a telephone." It's easy to snigger. Kim Jong-un looks like an overgrown schoolboy.

North Korea is a hell hole. Shut off from the rest of the world its people are starved as a policy decision and its economy - even calling it an economy feels like an exaggeration - is ruinously antiquated. Kim Jong-un hardly gives the impression of a leader whose very words should send fear down the spines of world leaders.

As threats to the world go North Korea seems more comical than lethal.

But do not be fooled. The reason North Korea is such a hell hole and its people so backward is precisely because its leaders are ruthless - and by all rational standards, mad. They do not bat an eyelid at starving their population to death.

In recent days North Korea has ratcheted up its anti-Western rhetoric to unprecedented levels. It is no longer making general threats about its capabilities and how it might one day behave. It is making specific, direct threats about where it will attack - and how.

On Thursday it warned that "the moment of explosion is near" and said its army had been instructed to ready itself to attack the US using "smaller, lighter and diversified" nuclear weapons. As we learned on 9/11 when madmen make threats they sometimes mean exactly what they say.

Certainly the US is taking the threat of a nuclear attack seriously. Yesterday North Korea moved to its east coast a missile that can attack up to 1,800 miles away, putting Japan within its range.

The US, meanwhile, is bolstering its ballistic missiles on Guam, the Pacific Island that North Korea has also threatened, and has just deployed a battalion of antinuclear weapons at a base near Seoul in South Korea.

This is not a game. It is a deadly serious response to the threat of possible nuclear war. And it is the result of a madman and a mad regime having nuclear weapons. No one knows where this will end.

Whatever happens next - and I wish I had the confidence that some seem to have that Kim Jong-un is simply huffing and puffing - it does not take a genius to deduce the key lesson that we should take from North Korea's behaviour. It is that it is not the greatest idea in history to let megalomaniac regimes have nuclear weapons.

Because frightening enough as the North Korean crisis is, there are other nuclear hotspots that may pose an even greater threat.

The tensions between India and Pakistan over Kashmir would be bad enough in a nonnuclear world. But with both nations already in possession of large quantities of nuclear weapons the omens are dire.

Today there is effective parity between India and Pakistan. The latter has more weapons, the former more advanced weapons. But the Pakistanis are engaged in a headlong rush to supersede the nuclear capability of their neighbour and present India with a fearsome nuclear threat. Pakistan is now as close to being a failed state as is possible without tipping over the edge. Politically it is chaotic. Economically it is in crisis. Socially it is imploding.

David Cameron on HMS Victorious after stating the importance of nuclear deterrence earlier this week

This is not a game. It is a deadly serious response to the threat of possible nuclear war

So long as semi-rational politicians and army chiefs are in charge there is hope that catastrophe can be avoided. But with every passing day the danger grows that jihadists will take over and seize a terrifying nuclear arsenal.

Then there is Iran. Although it does not yet possess nuclear weapons it is on the cusp, helped by Pakistani and North Korean technology.

A nuclear Iran is not merely a danger because it is the world's leading sponsor of terrorism and putting such capability in terrorists' hands is the nightmare scenario.

There is also a more strategic problem. Iran is bent on domination of the Middle East, as the least of its aims. This, it rightly believes, will come when it goes nuclear.

That means that the only rational response from other Middle Eastern powers is to match Iran's weapons, exacerbating the already terrifying regional instability that a nuclear Iran will bring.

So when David Cameron says, as he did on Thursday, that the British nuclear deterrent is as vital today as it was in the Cold War days he is stating the obvious.

As he put it: "Last year North Korea unveiled a long-range ballistic missile which it claims can reach the whole of the US. If this became a reality it would also affect the whole of Europe, including the UK."In the modern world of increasing nuclear proliferation it would be perverse - not to say suicidal - for us to unilaterally abandon our own deterrent.

Mr Cameron asked this potent question: "Does anyone seriously argue that it would be wise for Britain, faced with this evolving threat today, to surrender our deterrent?"

As he well knows the answer is yes because that is his coalition partners' position. Labour, once the home of CND, is now grown-up on defence. But the Lib Dems are as barking as ever. They want us to put our hands in the air and give up.

When it comes to the first objective of government, protecting the country, both Labour and the Conservatives are broadly sensible. As for the Lib Dems, let us all hope we never have to find out the consequences of their policy.